1. Field of Invention
The present invention relates to a trace layout method. More particularly, the present invention relates to a printed circuit board trace layout method.
2. Description of Related Art
In order to make behaviors of modern life more convenient, the current electronic device usually takes a portable form. A printed circuit board which is used to hold the electronic device constituting element needs to be miniaturized, lightened and fined. The printed circuit board is manufactured by way of printing and etching techniques, in which a large number of wires are taken to connect the parts with each other and also serve as the structure supporting the parts.
The wiring on the printed circuit board can be designed manually or automatically by a computer. Computer graphic technique are usually adopted in the process of automatic design. The computer graphic technique implemented on the printed circuit board by the computer mainly includes two stages: a placement operation and a subsequent layout operation. After the printed circuit board placement operation is finished, the subsequent layout operation is performed on the printed circuit board. In the layout operation, the width of the trace is determined according to the manufacturing technology and the required characteristics of an electric apparatus; the width of the trace is also closely related to the allowable current flux.
When the circuit layout engineer layout the traces, both the traces and the pads have different widths, respectfully. If the width of the traces is larger than that of the pads, which usually occurs, the short circuit might be caused. In order to avoid the short circuit situation, the layout engineer needs to search whether the width of the trace is larger than that of the pad and reduces the width of the over-width trace manually after the wiring procedure is substantially finished; otherwise, an additionally manual step is performed to reduce the width of the trace. However, such trace width correction procedure is time-consuming, and the wiring is neither flexible. In addition, the unavoidable human negligence also tends to cause the short circuit among traces and pads.